fanotify: info leak in copy_event_to_user()

commit de1e0c40aceb9d5bff09c3a3b97b2f1b178af53f upstream.

The ->reserved field isn't cleared so we leak one byte of stack
information to userspace.

Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Cc: Eric Paris <eparis@redhat.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>

diff --git a/fs/notify/fanotify/fanotify_user.c b/fs/notify/fanotify/fanotify_user.c
index 9fde1c0..9860f6b 100644 (file)
--- a/fs/notify/fanotify/fanotify_user.c
+++ b/fs/notify/fanotify/fanotify_user.c
@@ -118,6 +118,7 @@ static int fill_event_metadata(struct fsnotify_group *group,
        metadata->event_len = FAN_EVENT_METADATA_LEN;
        metadata->metadata_len = FAN_EVENT_METADATA_LEN;
        metadata->vers = FANOTIFY_METADATA_VERSION;
        metadata->event_len = FAN_EVENT_METADATA_LEN;
        metadata->metadata_len = FAN_EVENT_METADATA_LEN;
        metadata->vers = FANOTIFY_METADATA_VERSION;

+       metadata->reserved = 0;

        metadata->mask = event->mask & FAN_ALL_OUTGOING_EVENTS;
        metadata->pid = pid_vnr(event->tgid);
        if (unlikely(event->mask & FAN_Q_OVERFLOW))
        metadata->mask = event->mask & FAN_ALL_OUTGOING_EVENTS;
        metadata->pid = pid_vnr(event->tgid);
        if (unlikely(event->mask & FAN_Q_OVERFLOW))